A photo-thermal catalyst, a preparation method thereof and application of the photo-thermal catalyst in catalyzing dehydrogenation of liquid organic hydrogen carrier

Abstract

The application discloses a kind of photo-thermal catalyst and its preparation method and application in catalyzing liquid organic hydrogen carrier dehydrogenation, belong to hydrogen storage material dehydrogenation technical field.The photo-thermal catalyst is obtained by the substance M / S that metal M is uniformly dispersed on carrier S and rare earth hydride REH x Mixing;Wherein, metal M is platinum, palladium or nickel;S is γ type alumina, titanium dioxide, silicon dioxide or activated carbon;Rare earth RE in rare earth hydride REH x It is lanthanum, cerium, yttrium, gadolinium or praseodymium, and x=1.9~3.1.The photo-thermal catalyst has the characteristics of high photo-thermal conversion efficiency, wide spectral applicability and high catalytic activity, can use various different light sources to accurately heat the active sites on the catalyst surface, without heating the entire reaction device, significantly improving the energy utilization efficiency of catalytic hydrogen release.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage material dehydrogenation technology, specifically to a photothermal catalyst, its preparation method, and its application in the dehydrogenation of liquid organic hydrogen carriers. Background Technology

[0002] Liquid organic hydrogen carriers (LOHCs) are safe, stable, and high-capacity hydrogen storage materials, representing a crucial technological approach for efficient and safe hydrogen storage. LOHCs are typically based on the reversible conversion of aromatic and alicyclic compounds. Their dehydrogenation reactions involve the breaking of the CH4 chain, resulting in high activation energies. Furthermore, the dehydrogenation reaction is endothermic, leading to high dehydrogenation temperatures and requiring additional energy for hydrogen release. For example, the dehydrogenation temperature of organic liquids like hydrogenated N-ethylcarbazole (H12-NEC) and traditional thermal catalysts such as Pd / Al2O3 is typically between 180°C and 200°C. These issues result in high energy consumption for dehydrogenation, reducing the economic viability of LOHC applications. Photothermal catalysis, on the other hand, utilizes solar energy to precisely heat the catalyst surface, reducing the heat input required to maintain the thermal catalytic temperature and thus saving on dehydrogenation costs. Highly efficient photothermal catalysts are key to achieving efficient photothermal dehydrogenation.

[0003] Compared to conventional dehydrogenation catalysts, photothermal catalysts require high light absorption, high photothermal conversion efficiency, and synergistic effects between photothermal activity and catalytic sites. Currently, there are very few photothermal dehydrogenation catalysts applied to carbazole-based LOHC catalysts. Summary of the Invention

[0004] The purpose of this invention is to provide a photothermal catalyst with a simple preparation method and significantly improved catalytic activity, which can achieve rapid hydrogen release from LOHC hydrogenation and reduce reaction energy consumption.

[0005] The technical solution of this invention is as follows: In a first aspect, the present invention provides a photothermal catalyst comprising a substance M / S obtained by uniformly dispersing metal M on a support S and a rare earth hydride REH. x It is a mixture; wherein the metal M is platinum (Pt), palladium (Pd) or nickel (Ni); S is γ-alumina (γ-Al2O3), titanium dioxide (TiO2), silicon dioxide (SiO2) or activated carbon; the rare earth RE in the rare earth hydride REHx is lanthanum La, cerium Ce, yttrium Y, gadolinium Gd or praseodymium Pr, and x=1.9~3.1.

[0006] Optionally or preferably, the load of M in M / S is 0.1~5.0 wt.%, with the optimum being 1 wt.%.

[0007] Optional or preferred, M / S and REH x The mass ratio is 1:4 to 4:1, with the optimal ratio being 1:1.

[0008] Secondly, the present invention provides a method for preparing any of the above-described photothermal catalysts, wherein M / S and REH are... x Mix by grinding or ball milling in an argon atmosphere.

[0009] Optionally or preferably, the preparation method of M / S is to uniformly mix the precursor of metal M with the carrier S by solution impregnation, grinding or ball milling to obtain a mixture, and then heat the mixture to a set temperature under a set reaction atmosphere to obtain M / S.

[0010] A precursor to metal M refers to an intermediate compound containing the metallic element M that, under specific process conditions, can be decomposed / reacted into the target metallic element M, an alloy, or a metal-containing functional material (such as oxide or nitride thin films).

[0011] Thirdly, the present invention also provides the application of any of the above-described photothermal catalysts in the catalytic dehydrogenation of LOHC hydrogenation, wherein the photothermal catalyst is mixed with LOHC hydrogenation and then subjected to photoirradiation under an argon atmosphere to complete the catalytic dehydrogenation reaction; or... After mixing the photothermal catalyst with hydrogenated LOHC, the reactor containing the photothermal catalyst and hydrogenated LOHC mixture is irradiated under an argon atmosphere and additionally heated to a temperature not exceeding 250°C to complete the catalytic dehydrogenation reaction.

[0012] Irradiation can be achieved by direct sunlight or by using irradiation equipment such as xenon lamps.

[0013] Optionally or preferably, the liquid organic hydrogen carrier includes any one of the following: Fully hydrogenated N-ethylcarbazole; Fully hydrogenated N-methylcarbazole; Fully hydrogenated N-propylcarbazole; A mixture of at least two of the following: fully hydrogenated N-ethylcarbazole, fully hydrogenated N-methylcarbazole, and fully hydrogenated N-propylcarbazole; Fully hydrogenated dibenzyltoluene; Fully hydrogenated benzyltoluene; A mixture of fully hydrogenated dibenzyltoluene and fully hydrogenated benzyltoluene.

[0014] Optionally or preferably, the mass ratio of photothermal catalyst to hydrogenated LOHC is 1:100 to 100:1, with a preferred range of 1:10 to 5:1.

[0015] Optional or preferred, the light intensity is 100~3000 mW / cm². 2Methods for controlling light intensity include, but are not limited to, adjustment using optical components such as condenser lenses.

[0016] Optionally or preferably, the catalytic hydrogenation of LOHC dehydrogenation using a photothermal catalyst includes the following steps: (1) The photothermal catalyst and hydrogenated LOHC are mixed by grinding or ultrasonication to form a uniform slurry.

[0017] (2) The slurry is loaded into a reactor with a quartz window and argon gas is introduced to remove the air in the reactor; the reactor includes, but is not limited to, a columnar transparent reactor made of quartz material, with at least one transparent quartz surface on the top, bottom or side.

[0018] (3) The reactor temperature is controlled to not exceed 250°C, and the slurry is illuminated through a quartz window to catalyze the hydrogenation LOHC dehydrogenation reaction; the generated hydrogen is cooled to remove organic droplets; the reactor temperature control method includes, but is not limited to, using an external heating source such as an oil bath or heating element or external cooling water for temperature control.

[0019] (4) After the reaction is complete, the photothermal catalyst is separated from the dehydrogenated LOHC by filtration and / or centrifugation. The separated liquid product LOHC can be regenerated by hydrogenation to form a hydrogen-rich liquid organic hydrogen support, and the photothermal catalyst can be reused in the photothermal catalytic hydrogen release reaction.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The photothermal catalyst of this invention is a composite catalyst. The selected metal M has catalytic activity, and the support S is an oxide or carbon support with a high specific surface area. The substance M / S obtained by uniformly dispersing the metal M on the support S serves as the main catalyst. Rare earth metal hydrides are added to this transition metal dehydrogenation catalyst system M / S using a physical mixing method. The rare earth metal hydrides are photothermal aids with broad-spectrum light absorption and high-efficiency photothermal conversion performance. They can effectively increase the local temperature on the surface of the main catalyst under light irradiation, creating local hot spots. At the same time, the rare earth metal hydrides can efficiently transfer hydrogen atoms, further improving the catalytic dehydrogenation activity.

[0021] The photothermal catalyst of the present invention has the characteristics of high photothermal conversion efficiency, wide spectral applicability and high catalytic activity. It can use a variety of different light sources to precisely heat the active sites on the catalyst surface without heating the entire reaction device, which significantly improves the energy utilization efficiency of catalytic hydrogen release. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the co-catalyst YH3 used in Example 1 of the present invention.

[0023] Figure 2This is a scanning electron microscope image of the composite catalyst Pd / Al2O3-YH3 used in Example 1 of this invention.

[0024] Figure 3 These are powder X-ray diffraction patterns of the co-catalyst YH3 and the composite catalyst Pd / Al2O3-YH3 used in Example 1 of this invention.

[0025] Figure 4 This is the elemental distribution of the composite catalyst Pd / Al2O3-YH3 used in Example 1 of the present invention; where (a) is a STEM image; (bd) are the corresponding elemental imaging images: (b) Al; (c) Y; (d) Pd.

[0026] Figure 5 These are the ultraviolet-visible diffuse reflectance spectra of YH3, Pd / Al2O3, and Pd / Al2O3-YH3 used in Embodiment 1 of the present invention.

[0027] Figure 6 The composite catalyst used in Example 1 of this invention and the Pd / Al2O3 catalyst at 1070 W / cm 2 A comparison of photothermal catalytic hydrogen release effects under conditions of high illumination power and no other external heating source.

[0028] Figure 7 The composite catalyst used in Example 2 of this invention and the Pd / Al2O3 catalyst were heated at 195°C and simultaneously subjected to a 589 W / cm² temperature. 2 Comparison of photothermal catalytic hydrogen release effects under illumination power conditions.

[0029] Figure 8 This is a comparison of the photothermal catalytic hydrogen release effect of the composite catalyst used in Example 3 of the present invention with that of Pd / Al2O3. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present application, the present application will be clearly and completely described below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application. Unless otherwise specified, the instruments, equipment, and reagents used in the embodiments are all from commercial channels.

[0031] Example 1: Preparation of Pd / Al2O3-YH3 composite catalyst and its catalytic dehydrogenation of H12-NEC under single light irradiation S1: 28.8 mg of palladium acetylacetonate (a precursor of metallic Pd) was ground and mixed with 1 g of dehydrated γ-alumina powder for 10 min. The mixture was then thermally decomposed at 240 °C in air for 4 h to obtain the main catalyst Pd / Al2O3, in which the Pd content was 1 wt.%.

[0032] Yttrium fragments were loaded into a high-pressure tubular furnace and heated to 350°C under vacuum. Hydrogen gas at 4 MPa was then introduced to absorb hydrogen, yielding the co-catalyst YH3. Scanning electron microscopy images of YH3 are shown below. Figure 1 As shown.

[0033] Pd / Al₂O₃ and YH₃ were ground and mixed uniformly at a mass ratio of 1:1 for 10 min under an inert atmosphere (argon) to obtain the composite catalyst Pd / Al₂O₃-YH₃. Its scanning electron microscopy image is shown below. Figure 2 As shown.

[0034] Powder X-ray diffraction patterns of co-catalyst YH3 and composite catalyst Pd / Al2O3-YH3 are shown below. Figure 3 As shown. The elemental distribution of the Pd / Al2O3-YH3 composite catalyst is as follows. Figure 4 As shown. The UV-Vis diffuse reflectance spectra of YH3, Pd / Al2O3, and Pd / Al2O3-YH3 are as follows. Figure 5 As shown.

[0035] S2: Take 0.15g of the composite catalyst Pd / Al2O3-YH3 obtained in step S1 and 1.5g of H12-NEC (fully hydrogenated N-ethylcarbazole) and add them to a quartz reactor with a vacuum insulation layer. After sealing the interface with vacuum grease, ultrasonically mix for 5min in an ultrasonic machine to obtain the reaction slurry system.

[0036] S3: Connect the quartz reactor to the flow meter and then to the hydrogen supply unit.

[0037] S4: Turn on the Xe lamps to illuminate the bottom of the reactor, with a light power density of 1070 mW / cm². 2 Record traffic information.

[0038] S5: After the reaction was completed, the substrate was centrifuged under an inert atmosphere. The separated solid composite catalyst Pd / Al2O3-YH3 was washed three times with acetone and then dried in a vacuum for 12 hours.

[0039] In this embodiment, starting from step S2, a single co-catalyst YH3 and a single main catalyst Pd / Al2O3 of the same mass as the composite catalyst Pd / Al2O3-YH3 are simultaneously set as a control experiment.

[0040] A comparison of the reaction performance using the composite catalyst Pd / Al2O3-YH3 and the catalyst Pd / Al2O3 is shown below. Figure 6 It is evident that, when relying solely on light for energy, the composite catalyst Pd / Al2O3-YH3 exhibits significantly superior catalytic dehydrogenation performance compared to Pd / Al2O3.

[0041] Example 2: Catalytic dehydrogenation of H12-NEC by Pd / Al2O3-YH3 composite catalyst under light and heating S1: Select the same catalyst Pd / Al2O3-YH3 as step S1 in Example 1.

[0042] S2: Take 0.1g of the composite catalyst Pd / Al2O3-YH3 obtained in step S1 and 1g of H12-NEC and add them to the columnar quartz reactor. After sealing the interface with vacuum grease, ultrasonically mix them for 5min in an ultrasonic machine to obtain the reaction slurry system.

[0043] S3: Connect the quartz reactor to the flow meter and then to the hydrogen supply unit.

[0044] S4: After heating the oil bath to 195℃, immerse the quartz reactor connected to the flow meter into the oil bath and turn on the Xe lamp to illuminate from the top, with a light power density of 589 mW / cm². 2 Record traffic information, see [link / reference] Figure 7 The results showed that 458 mL of hydrogen gas was released within 120 min.

[0045] S5: After the reaction was completed, the substrate was centrifuged under an inert atmosphere. The separated solid composite catalyst Pd / Al2O3-YH3 was washed three times with acetone and then dried in a vacuum for 12 hours.

[0046] In step S2 of this embodiment, a Pd / Al2O3 catalyst of the same mass as the composite catalyst Pd / Al2O3-YH3 is used as a control experiment to examine the role of YH3.

[0047] The results showed that, under conditions of weak ambient light intensity and reactor heating, the performance of the composite catalyst Pd / Al2O3-YH3 was still superior to that of the Pd / Al2O3 catalyst. The comparison with Example 1 also showed that irradiating the catalyst (i.e., precise directional energy supply to the catalyst) is more effective than heating the entire reaction vessel in promoting the dehydrogenation reaction of H12-NEC.

[0048] Example 3 S1: Select the same catalyst Pd / Al2O3 as in step S1 of Example 1.

[0049] Gadolinium and praseodymium fragments were loaded into a high-pressure tubular furnace and heated to 277°C under vacuum conditions. Hydrogen gas at 4 MPa was then introduced to absorb hydrogen, yielding co-catalysts GdH3 and PrH3.

[0050] Pd / Al2O3 and REH3 were ground and mixed uniformly at a mass ratio of 1:1 for 10 min under an inert atmosphere to obtain composite catalysts Pd / Al2O3-GdH3 and Pd / Al2O3-GdH3.

[0051] S2: Take 0.15g of the composite catalyst Pd / Al2O3-GdH3 or Pd / Al2O3-GdH3 obtained in step S1 and 1.5g of H12-NEC and add them to a quartz reactor with a vacuum insulation layer. After sealing the interface with vacuum grease, ultrasonically mix for 5min in an ultrasonic machine to obtain the reaction slurry system.

[0052] S3: Connect the quartz reactor to the flow meter and then to the hydrogen supply unit.

[0053] S4: Turn on the Xe lamps to illuminate the bottom of the reactor, with a light power density of 1070 mW / cm². 2 Record traffic information.

[0054] S5: After the reaction is complete, the substrate is centrifuged under an inert atmosphere. The separated solid composite catalyst is washed three times with acetone and then dried in a vacuum for 12 hours.

[0055] The results are as follows Figure 8 As shown, replacing some of the metal RE in the co-catalyst REH3 with other rare earth elements also significantly enhances the photothermal catalytic hydrogen release effect.

[0056] Example 4: Dehydrogenation of H12-NEC catalyzed by Co-B / Al2O3-YH3 under photothermal conditions S1: 0.5 g of γ-Al2O3 solid was ultrasonically dispersed in 10 mL of a 0.5 mol / L solution. -1 In a CoCl2 solution, 5 mL of a 10 wt% NaBH4 solution was slowly added to the suspension until no more bubbles were generated. The mixture was then centrifuged and vacuum dried to obtain the Co-B / Al2O3 catalyst, in which the Co-B loading was 6.5 wt%.

[0057] S2: Co-B / Al2O3 and YH3 were ground and mixed evenly at a mass ratio of 1:1 for 10 min under an inert atmosphere (argon) to obtain the composite catalyst Co-B / Al2O3-YH3.

[0058] S3: Take 0.1g of the composite catalyst Co-B / Al2O3-YH3 obtained in step S2 and 1g of H12-NEC and add them to the columnar quartz reactor. After sealing the interface with vacuum grease, mix them ultrasonically in an ultrasonic machine for 5 minutes to obtain the reaction slurry system.

[0059] S4: Connect the quartz reactor to the flow meter and then to the hydrogen supply unit.

[0060] S5: Turn on the Xe lamps to illuminate the bottom of the reactor, with a light power density of 1070 mW / cm². 2 The flow rate information was recorded. The results showed that 150 mL of hydrogen gas was released within 120 minutes. In Example 1, approximately 800 mL of hydrogen gas was released within 120 minutes under the same light power.

[0061] S6: After the reaction was completed, the substrate was centrifuged under an inert atmosphere. The separated solid composite catalyst Co-B / Al2O3-YH3 was washed three times with acetone and then dried in a vacuum for 12 h.

[0062] A comparison with Example 1 shows that the type of transition metal in the composite photothermal catalyst with added rare earth hydrides also has a significant impact on the dehydrogenation performance.

[0063] This article uses specific examples to illustrate the inventive concept in detail. The description of the above embodiments is only for the purpose of helping to understand the core idea of ​​the present invention. It should be noted that any obvious modifications, equivalent substitutions or other improvements made by those skilled in the art without departing from the inventive concept should be included within the protection scope of the present invention.

Claims

1. A photothermal catalyst, characterized in that, The substance M / S obtained by uniformly dispersing metal M on support S and rare earth hydride REH x It is a mixture; wherein, metal M is platinum, palladium or nickel; S is γ-alumina, titanium dioxide, silicon dioxide or activated carbon; rare earth hydride REH x The rare earth elements (RE) in the sample are lanthanum, cerium, yttrium, gadolinium, or praseodymium, with x = 1.9~3.

1.

2. The photothermal catalyst according to claim 1, characterized in that, The load of M in M / S is 0.1~5.0 wt.%.

3. The photothermal catalyst according to claim 1, characterized in that, M / S and REH x The mass ratio is 1:4 to 4:

1.

4. The method for preparing the photothermal catalyst according to any one of claims 1 to 3, characterized in that, M / S and REH x Mix by grinding or ball milling in an argon atmosphere.

5. The method for preparing the photothermal catalyst according to claim 4, characterized in that, The preparation method of M / S is to uniformly mix the precursor of metal M with the carrier S by solution impregnation, grinding or ball milling to obtain a mixture. The mixture is heated to a set temperature under a set reaction atmosphere to obtain M / S.

6. The application of the photothermal catalyst according to any one of claims 1 to 3 in the catalytic hydrogenation and dehydrogenation of LOHC, characterized in that, The photothermal catalyst is mixed with hydrogenated LOHC and then subjected to photocatalytic dehydrogenation under an argon atmosphere; or... After mixing the photothermal catalyst with hydrogenated LOHC, the reactor containing the photothermal catalyst and hydrogenated LOHC mixture is irradiated under an argon atmosphere and additionally heated to a temperature not exceeding 250°C to complete the catalytic dehydrogenation reaction.

7. The application according to claim 6, characterized in that, The liquid organic hydrogen carrier includes any one of the following: Fully hydrogenated N-ethylcarbazole; Fully hydrogenated N-methylcarbazole; Fully hydrogenated N-propylcarbazole; A mixture of at least two of the following: fully hydrogenated N-ethylcarbazole, fully hydrogenated N-methylcarbazole, and fully hydrogenated N-propylcarbazole; Fully hydrogenated dibenzyltoluene; Fully hydrogenated benzyltoluene; A mixture of fully hydrogenated dibenzyltoluene and fully hydrogenated benzyltoluene.

8. The application according to claim 6, characterized in that, The mass ratio of photothermal catalyst to hydrogenated LOHC is 1:100~100:

1.

9. The application according to claim 6, characterized in that, Illumination intensity is 100~3000 mW / cm 2 .

10. The application according to claims 6-9, characterized in that, The catalytic hydrogenation of LOHC using a photothermal catalyst includes the following steps: (1) The photothermal catalyst and hydrogenated LOHC are mixed by grinding or ultrasonication to form a uniform slurry; (2) The slurry is loaded into a reactor with a quartz window and argon gas is introduced to remove the air in the reactor; (3) Control the reactor temperature to not exceed 250℃, and at the same time irradiate the slurry through the quartz window to catalyze the hydrogenation LOHC dehydrogenation reaction; the generated hydrogen is cooled to remove organic droplets; (4) After the reaction is completed, the photothermal catalyst is separated from the dehydrogenated LOHC by filtration and / or centrifugation.

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